Flash point analyzer



Filed Oct. 15. 1963 Sample Out (Vic Vapor Trap) Te mp- Recorder Air InINVENTOR. CONARD K. DONNELL BY 2 f ATTORNEY United States Patent Thisinvention relates to a flash point analyzer, and more particularly to anautomatic, continuous flash point analyzer.

Certain liquid hydrocarbon products (e.g., household fuel oil) musthave, as one of their specifications for marketing purposes, a statedflash point. It is important, therefore, to ascertain the flash point(stated as a temperature) of such products during manufacture thereof.Also, the flash points of other flammable liquids (such as hydrocarboncleaning fluids, paint solvents, etc.) are important characteristics ofsuch liquids, such that these flash points need to be determined.

The flash point of a combustible material (e.g., a combustible liquidhydrocarbon) is defined as the temperature at which its vapors firstignite, under specified conditions, in a laboratory test. Theseconditions must be controlled carefully, and considerable skill isrequired of the operator to obtain reproducible results.

Several different automatic flash point analyzers are being marketed,these analyzers giving more consistent results than the laboratory testsbecause their operating cycles are controlled automatically; that is tosay, their results do not depend on the skill of the operator.

All of the prior automatic flash point analyzers are cyclic instrumentswhich are similar in principle to the laboratory procedure, beingprogrammed through a temperature cycle to give an intermittent readingof the flash point temperature. In allcases, the ignition temperature isdetermined by introducing a flame or spark intermittently into the vaporspace of the flash chamber.

It would be highly advantageous to have a continuous indication (orrecord) of the flash point temperature, rather than only an intermittentone as in the prior de-- vlCES.

Accordingly, an object of this invention is to provide a flash pointanalyzer which gives a continuous output of intelligence, that is, acontinuous indication of the flash point.

Another object is to provide a novel flash point analyzer.

The objects of this invention are accomplished, briefly, in thefollowing manner: A continuous combustion detector, in the form of ahot-wire combustion meter, produces and detects the ignition of acombustible gaseous mixture emanating from a heated chamber operating asa flash vaporizer, and this detector in turn controls the temperature ofthe heated chamber. The temperature of the heated chamber is socontrolled that the rate of vaporization of the combustible liquid beingfed to this chamber is just suflicient to provide a combustible mixtureat the detector. The temperature of the chamber is recordedcontinuously.

A detailed description of the invention follows, taken in conjunctionwith the accompanying drawing, wherein the single figure is a schematicdiagram of a flash point analyzer according to the invention.

Referring now to the drawing, a sample of a combustible liquid (e.g., acombustible liquid hydrocarbon such as furnace oil) flows by means of asample inlet line 1 into a sample chamber 2, at a constant rate. Thesample chamber 2 is elongated in the vertical direction, for example,and the sample inlet line 1 enters the upper end of this chamber in sucha manner that the sample liquid, as it enters the upper end of thechamher 2 and flows downwardly, forms a thin liquid film on the chamberWalls. Liquid sample which is not vaporized in chamber 2 drains outthrough an outlet line 3 connected to the bottom of the chamber, througha suitable vapor trap (not shown) of conventional design.

Sample chamber 2 is arranged to operate as a flash vaporizer for theliquid sample, this chamber being heated to a temperature at which asmall amount of vapor is produced therein. This heating is efiected bymeans of an electrically-energized heater 4 surrounding chamber 2, inheat-transmitting relationship therewith. The energization of heater 4is controlled by a temperature controller 5, which will be furtherreferred to hereinafter.

A thermocouple 6 is utilized to sense the temperature at the inside wallof chamber Z. This thermocouple is connected by a pair of leads 7 to arecorder 8, which is continuously records the temperature sensed bythermocouple 6 (that is, the temperature of chamber 2).

Air is introduced by means of a pipe 9 into the bot tom of chamber 2,which latter may be thought of as a vaporizer. This air forms, with thevapor produced in vaporizer 2, a combustible gaseous mixture, whichmixture is swept by the air out the top of chamber 2 through a flamearrester 10 to a combustion detector 11.

The vapor trap in the sample outlet line 3 prevents the escape of vaporsthrough such line. Detector 11 is preferably a hot-wire combustion meterof conventional type, comprising a heated wire connected into a bridgenetwork. Detector (meter) 11 operates to ignite the combustible mixturereaching it via flame arrester 10, and to produce a signal at its output12 which is proportional to the concentration of combustible vapor inthe combustible mixture.

The signal appearing on output lead 12 (that is to say, the signalproduced by detector 11) is applied to temperature controller 5, as theinput signal therefor. Controller 5 is of the so-called ProportionalController with Reset type, and operates (in response to the signal fedto it at 12) to control or regulate the power supplied to the vaporizerheater 4. This it does by controlling the energization of thiselectrically-energized heater. The set point of controller 5 is soadjusted as to maintain (by control of the heater 4 by said controller)chamber 2 at a temperature such that the rate of vaporization of theliquid sample is just sufficient to provide a combustible mixture atdetector 11. In other words, chamber 2 is maintained at the lowesttemperature at which enough vapor is produced to flash in detector 11.

If for some reason the temperature of the vaporizer (chamber 2)increases, the amount of combustible vapor in the vapor stream moving todetector 11 would increase. The resulting increase in the output ofmeter 11 would signal the controller 5 to reduce the vaporizertemperature, by reducing the energization of heater 4. The oppositeaction occurs if the temperature of the vaporizer decreases. Thus, thevaporizer temperature is controlled at a point where vaporization justbegins in the vaporizer 2. The vaporizer temperature is recorded, byrecorder 8, as the flash point temperature of the sample.

The flame arrester 10 may be of any well-known construction (e.g., anarrangement of screens, or steel wool, etc.) for preventing flashback.This arrester is required to prevent flashback from the combustion meter11 into the vaporizing chamber 2. Burning must not occur in thevaporizer 2, because this would interfere with the proper operation ofthe combustion meter 11. In addition, the heat of combustion would heatthe vaporizer 2 independently of the electrical heater 4, and thetemperature controller 5 would lose control.

It is pointed out that the temperature control of the vaporizer 2 (bymeans of heater 4, controlled from controller 5) is continuous, and thatthe recording of this temperature (on recorder 8, the temperature beingsensed by thermocouple 6) is also continuous. Thus, a continuous recordof the flash point of the liquid sample is produced.

t is desired to be pointed out that the device of the present inventionprovides another advantage. If combustion took place in chamber 2 (as itdoes in devices of the prior art), rather than in detector 11, foulingwould occur much more rapidly than it does in the present device; thatis to say, the meter 11 does not become fouled, as a result ofcombustion, nearly as fast as would the chamber 2.

The invention claimed is:

1. A flash point analyzer comprising a sample chamber, means for flowinga sample of a combustible liquid into said chamber, controllable meansfor heating said chamber to cause it to act as a flash vaporizer forsaid liquid, a hot-wire combustion meter separate from said chamber andspaced therefrom, means providing a gaseous flow path between said meterand the interior of said chamber; said meter operating to ignite thecombustible gaseous mixture reaching the same solely by way of said flowpath and to produce a signal proportional to the concentration ofcombustible vapor in such mixture; and means receptive of said signalfor controlling said heating means in dependence upon said signal.

2. An analyzer as set forth in claim 1, wherein the last-mentioned meanscontrols said heating means to maintain said chamber at a temperaturesuch that the rate of vaporization of said liquid is just sui'licient toprovide a combustible mixture at said meter.

3. An analyzer in according with claim 1, including also a flamearrester in said gaseous flow path, between said chamber and said meter.

References Cited by the Examiner UNITED STATES PATENTS 1,686,051 10/28Weber 48-492 X 2,627,745 2/53 Matteson 73-36 2,746,285 5/56 Greanias7336 2,746,286 5/56 Greanias et a1. 73-36 2,752,776 7/56 Kaptf et a1.7336 3,011,337 12/61 McGlynn 73--36 RICHARD C. QUEISSER, PrimaryExaminer.

DAVID SCHONBERG, Examiner.

1. A FLASH POINT ANALYZER COMPRISING A SAMPLE CHAMBER, MEANS FOR FLOWINGA SAMPLE OF A COMBUSTIBLE LIQUID INTO SAID CHAMBER, CONTROLLABLE MEANSFOR HEATING SAID CHAMBER TO CAUSE IT TO ACT AS A FLASH VAPORIZER FORSAID LIQUID, A HOT-WIRE COMBUSTION METER SEPARATE FROM SAID CHAMBER ANDSPACED THEREFROM, MEANS PROVIDING A GASEOUS FLOW PATH BETWEEN SAID METERAND THE INTERIOR OF SAID CHAMBER; SAID METER OPERATING TO IGNITE THECOMBUSTIBLE GASEOUS MIXTURE REACHING THE SAME SOLELY BY WAY OF SAID FLOWPATH AND TO PRODUCE A SIGNAL PROPORTIONAL TO THE CONCENTRATION OFCOMBUSTIBLE VAPOR IN SUCH MIXTURE; AND MEANS RECEPTIVE OF SAID SIGNALFOR CONTROLLING SAID HEATING MEANS IN DEPENDENCE UPON SAID SIGNAL.